Saturating paper



Patented Mar. '19, 1929.

UNITED STATES PATENT oFFica.

REED 1?. ROSE, OF JACKSON HEIGHTS, AND HAROLD E. CUDE, OF FLORAL PARK, NEW

YORK, ASSIGNORS. TO GENERAL RUBBER COMPANY, OF NEW YORK, N. Y., A COR.-

ron'a'rron on NEW JERSEY.

SATURATING PAPER.

ll'o Drawing.

remove fats, oils, Waxes, and ligneous substance, and to disintegrate the 'cotton fibre itself. Fairly high concentrations of caustic soda and comparatively long cooking periods and high temperatures .are employed toac complish this purpose. Or the time may be shortened by elevating the temperature ordinarily employed." The result of the chem1- cal treatment'is the production of a fibre which disintegrates easily in the beater after say an hours beating and 'ves a sheet of finished paper having high a sorptive power for aqueous impregnating compositions, but having no appreciable strength. Rope stock, often mixed with sulphate pulp, is used in the manufacture of saturating papers of the type which are impregnated with glue-glycerine combinations for use as gasket material and the like. Such sheet materials are considerably stronger than the blotting papers, the latterbeing not adapted for glue-glycerine saturation on account of their low strength. On the other hand gasket materials made from rope fibre have but little absorptive, ower.- This 'is overcome to some extent y making the aper light and porous by mechanical mampula tion on the paper machine, as for example 40 by. running the machine very slowly and by eliminating the greater portion of the calendering step on the finished sheet.

According to the present invention a paper product can be made with a high tear a resistance and at the same time preserving all the other:useful properties of the fibre. This is one ofthe objects of the invention. Another object is to provide an improved method. for cooking vegetable fibres. -A further object is to remove fats,iwax, and

other naturally occurringmon-cellulosic materials from raw ,co'tton fibres without Application filed December 11, 1925. Serial No. 74,888.

greatly decreasingthe strength of the fibres. A still further object is to increase the saturating properties of papers. Yet another object is to prepare saturating papers hav-' ing an increased strength. It is also an object of the invention to treat such saturating papers with dispersions or solutions of plastic materials such as rubber, glue-glycerine, and other impregnating materials...

Other objects will be apparent from the specification and claim.

The invention briefly stated consists in treating cotton fibre with a mild alkaline reagent at a comparatively low temperature for such a period of time that; the strength of the-fibre 1s not materially reduced but the waxes, fats, and other naturally occurring materials are removed 'from the cellulose. The invention also includes forming such a cooked fibres into sheets and saturating the sheets thus produced with natural or artificial aqueous dispersions of rubber, with glue-glycerine combinations, with oils and other impregnating compositions known in the arts. The invention contemplates saturating the paper with one or more of the above materials separately or successively or in admixture.

Raw cotton linter or any kind of cotton fibres may be employed as the fibre. Cotton rags or cotton waste may be utilized, but

.it is preferred to use raw cotton fibre or new rags or waste rather than old material.

Waste fibre, such as rags and the like which has previously been cooked to remove the wax, may be mixed with raw cotton fibres, if desired.

In carrying out-the invention, 2700 lbs. of

rawcotton linter .are cooked with 342 lbs.

of 58%soda ash (which amounts to about 5-9% on the ,raw linter) in the presence of 5000 gallons of water. The final concentration of thecooking liquor should not be higher than 0.5%. The cooking can be done in an of the well-known cookers." In this speci c illustration a horizontal rotary cooker is used. The cooking is carried out at approximately 230 F. or at a maximum steam pressureof approximately 5 lbs. per

. inch,- the length of. time being 1 hrs.

0 temperature'during the first 40 min. of the cooking does not exceed an average of 120 F. It appears essential that the temperature should not be allowed to become too high. With the steam pressure given above, the time limit for the cooking should not exceed 3 hrs. and it is 'not desirable to use higher temperatures in order to shorten the cooking time owing to the great increase in the speed of the chemical reaction with "comparatively small increase in tem erature. The liquor is drained out o the cooker and the latter is filled with clean water and agitated for say hr. to wash out the soda. The washing may be carried out just as satisfactorily in a beater washer.

An hours washing in the beater is usually,

sufiicient. a

. The fibre, cleansed of the fats, wax, etc., is now beaten preparatory to making paper. With the cooking given above and with the type of raw material, 1% hrs. is usually a sufficient time for the beating. out, however, that the beating time may vary with difierent types of heaters and may be shortened or increased depending on the type of the product desired. The beating is done in conformance with standard practice.

The invention is not limited to the propor- Filling materials, colors and vulcanizing in gredients (when rubber is incorporated) may be added to the contents of the beater. It may be desirable to use a blend of paper making materials, that is to add woodpulp or other paper stocks together with the cotton fibre. I a

The saturating paper thus-obtained will absorb such materials as glue, glycerine, natural and artificial latex, and other materials in solution or suspension very much more rapidly than the best rope (or mixtures; of rope and other fibres) saturating paper's.

If latex be poured upon a sheet of the aper it will'be found that the latex strikes through the paper in a few seconds and appears underneath as latex, indicating that there has been no separation of the rubber from the aqueousfportion of the latex. In many instances inthe present practice saturation properties may be obtained, but no addition is made to the strength, and frequently there is an actual lossof strength. For example,

treating. ordinary saturating paper with latex does not add to the strength of the paper. In the present invention, however, treatment with u latex materially increases It-is pointedthe strength of the saturating paper. An-

other illustration of the saturating valueof, the paper made accordin to the present 1nvention is the speed wit which the paper will'absorb the glue-glycerine compositions of the type ordinarily employed in the manufacture of paper gaskets, etc. (Drdinary saturating paper will take up 7 O.80% of its weight of glue-glycerine compound, but the latter must be heated to PLO-160 F. inorder for proper saturation-to take place. With paper made according to the present process, the glue-glycerine mixture need not be heated at all, for at ordinary temperatures it penetrates at least three times as rapidly as the heated composition will penetrate ordinary saturating .paper. Latex may be combined with the glue-glycerine composition and the paper saturated at ordinary temperatures. This combination could not be absorbed at all by the usual types of saturating'paper for the rubber contained in the mixture would filter out on the surface of the sheet.

With the best grades of saturating papers heretofore known, (after saturation with latex) a tear resistance of 700 by the Elmen-' dorf method is well nigh unobtainable, irrespective of whether the paper has been j saturated or not. The paper made according to the present invention has atear resistance of more than 800 on the same weight sheet before saturation and from 800'; to"

1500 or even higher after treatment with latex or other materials. Tear resistances of this magnitude are unknown in the ordinary manufacture of paper. The present paper saturates much more rapidly and absorbs greater amounts of solution, than the ordinary papers. This gives'the paper of the present invention a much higher efficiency in the use to which it is put, for it can be made to contain greater amounts of the absorbed material than \is possible with the ordinary types of saturating paper. The saturating paper prepared according to the above examples has also the ability to absorb varnishes of various sorts such as the insulating varnishes and other coatings and impregnating liquids used in -the various industries. ,9Phen0lic condensation products in the liquidastage or in solution may be absorbed'into'the paper and subsequently harde'ned. The saturating paper thus prepared lends itself readily to the application of various kinds of coatings in the -manufacture of'coated papers. Its 'whole structure permits the ready ingress of adhesive solutions in which respect the paper has a certain utility as axbacking for cloth and other surfacing materials. I

In the claim, the term uewaxed is we claim and desire to protect by Letters plastiesubstance from a dispersion thereof Patent is: into the body of the sheet. 1 A process for making sheet material which Signed at New York, county and State of comprises mildly cooking cotton fibre to re- New York, this 8th day' of December, 1925.

5 move fats, oils, waxes, and other non-cel1u-' REED P. ROSE.

losie material therefrom without impairing Signed at New York, county and State of the strength of the fibre, making the cooked New York, this 8th day of December, 1925. fibre into a. sheet material, and absorbing a HAROLD E. CUDE. 

